By: Thomas Pickering, MD, DPhil, FRCP, Director of Integrative and Behavioral Cardiology Program
of the Cardiovascular Institute at Mount Sinai School of Medicine, New York.

It is well established that people who exercise regularly are at reduced risk of having a heart attack, but it is less certain whether it also protects against strokes. Now the Nurses’ Health Study, which we have often quoted before, has examined this question. It involves more than 72,000 nurses, who have been reporting on their lifestyles and health since 1986. The questions about physical activity asked them about walking, running, bicycling, aerobics, tennis, etc., and also how vigorously they did these various activities. During eight years of follow-up, there were 407 strokes, and it was found that the women who were more physically active were at lower risk. This was still true even after allowing for the facts that they were thinner, less likely to smoke, and ate better diets than the less active women. The lowest risk was in the most active women, whose average weekly activity was equivalent to 20 hours of walking, and whose risk was about half the risk of the inactive women. Strokes can have different causes, the commonest being ischemic strokes (from a blocked artery going to the brain), and the next most common hemorrhagic strokes (from a burst artery). The protective effect of exercise was greater for the ischemic type of stroke.

Doctor’s comments

This study provides the most convincing evidence to date that regular exercise protects against stroke, in addition to its other benefits. There was a graded relationship between activity and stroke, such that for every 3.5 hours of walking every week, the risk of stroke was reduced by 20%.

Where it was published